Thermographic inspection for tape layup machines

ABSTRACT

Systems and methods are provided for thermal inspection of tape layup. One embodiment is a method for performing inspection of a tape layup. The method comprises laying up tape onto a surface of a laminate, applying heat to tack the tape to the surface, and generating thermographic images of the tape as applied to the surface.

FIELD

The disclosure relates to the field of fabrication, and in particular,to tape layup machines that create laminates comprising multiple layersof tape.

BACKGROUND

Multi-layer laminates of constituent material (e.g., Carbon FiberReinforced Polymer (CFRP)) may be formed into any of a variety of shapesfor curing into a composite part. To facilitate the fabrication ofcomposite parts, a tape layup machine, such as an Automated FiberPlacement (AFP) machine or Automated Tape Layup (ATL) machine, may beutilized. For example, a tape layup machine may lay up one or morelayers of tows of constituent material that form a laminate which isthen hardened (e.g., cured or consolidated) to form a composite part.

The operations of a tape layup machine may be directed by a NumericalControl (NC) program that dictates movements of the tape layup machine.A tape layup machine may dispense multiple tows at once onto a laminatein a single course (e.g., a single “run” across a laminate), and a tapelayup machine may initiate or terminate individual lanes of tape withina course at different locations, in response to instructions from the NCprogram.

The final laminate generated by a tape layup machine may vary from whatis intended in an NC program, owing to factors that are not alwayscontrollable. For example, lanes of tape may be placed some distanceapart from their intended locations due to the machine being in need ofcalibration, foreign debris may fall onto the laminate, and fabricationinconsistencies such as twists or folds within a lane of tape may occurowing to inconsistencies in the lamination process. These conditions aredifficult to visually detect during layup, because lanes of tape aremade of the same material and hence are the same color (e.g., black).Furthermore, human inspection of a laminate prior to curing may resultin additional foreign debris (e.g., lint, etc.) landing upon thelaminate. Furthermore, current inspection techniques do not allow realtime course by course inspection of the lay down process. Theabove-recited problems also apply to laminates made from tapes that arenot fiber reinforced, and laminates that are not capable of hardeninginto composite parts. It is desirable to detect all conditions describedabove, and especially desirable to detect conditions cause portions oflayup to be out of tolerance.

It remains possible to perform inspection of a composite part viaultrasonic techniques after hardening a laminate. However, if out oftolerance conditions within the composite part indicate a level ofquality below a desired level, the entire composite part may need to bereworked or discarded. For large composite parts such as aircraft wings,a single reworked or discarded composite part results in a substantialwaste of resources, time, and labor.

Therefore, it would be desirable to have a method and apparatus thattake into account at least some of the issues discussed above, as wellas other possible issues.

SUMMARY

Embodiments described herein include thermographic inspection systemsthat are mounted to the head of a tape layup machine. These inspectionsystems utilize infrared cameras to acquire thermal images of lanes oftape applied by the head. Different portions of the laminate willexhibit different temperatures, depending on whether they are theunderlying laminate, foreign debris, or lanes of tape applied atop theunderlying laminate. For example, a heater at the head may generate adetectable temperature difference between the underlying laminate andthe lanes of tape, by heating either the underlying laminate or thelanes of tape. In a further example, a heater may heat both a laminateand a foreign object on the laminate. However, because the laminate andthe foreign object have fundamentally different thermal properties, theforeign object will respond to the application of heat differently thanthe underlying laminate, resulting in a detectable difference intemperature. These differences are detected by reviewing thermal imagesacquired during the layup process. The location and nature of featuresthat impact the quality of the laminate may therefore be reliablydetected and reported, by analyzing thermal images from infrared camerasmounted to a head of the tape layup machine. One embodiment is a methodfor performing inspection of a tape layup. The method comprises layingup tape onto a surface of a laminate, applying heat to tack the tape tothe surface, and generating thermographic images of the tape as appliedto the surface.

A further embodiment is a method for determining applied tapeboundaries. The method includes laying up lanes of tape onto a surfaceof a laminate, applying heat to tack the lanes of tape to the surface ofthe laminate, generating thermographic images of the lanes of tape asapplied to the laminate, analyzing contrast within the thermographicimages to identify the lanes of tape, and reporting locations of ends ofthe lanes of tape, based on boundaries depicted in the thermographicimages.

A further embodiment is a non-transitory computer readable mediumembodying programmed instructions which, when executed by a processor,are operable for performing a method for performing tape layupinspection. The method includes laying up lanes of tape onto a surfaceof a laminate, applying heat to tack the lanes of tape to the surface ofthe laminate, generating thermographic images of the lanes of tape asapplied to the laminate, analyzing contrast within the thermographicimages to identify the lanes of tape, and reporting locations of ends ofthe lanes of tape, based on boundaries depicted in the thermographicimages.

A still further embodiment is a tape layup end detection system. Thesystem includes a head of a tape layup machine. The head includes tapedispensers that lay up lanes of tape onto a surface of a laminate, aheater that applies heat to tack the lanes of tape to the surface, andan infrared camera disposed downstream of the tape dispensers thatgenerates thermographic images of the lanes of tape as applied to thelaminate. The system also includes a controller that analyzes contrastwithin the thermographic images to identify the lanes of tape, andreports locations of ends of the lanes of tape, based on boundariesdepicted in the thermographic images.

A still further embodiment is a method of controlling a tape layingprocess. The method comprises laying up tape on surface, while laying upthe tape, inspecting the surface on which it is laid up as well as thelaid-up tape using IR imaging, reviewing the IR imaging for out oftolerance conditions, and stopping the tape laying if an out oftolerance condition is detected.

A still further embodiment is a method of detecting out of toleranceinconsistencies during a tape laying process. The method comprisesheating a surface on which a tape will be applied, acquiring an IR imageof the surface, and determining that an out of tolerance inconsistencyis depicted in the IR image.

A still further embodiment is a method of inspecting a compositesurface. The method includes creating temperature differentials on asurface that has been heated, detecting the temperature differentials onthe surface, and determining that an out of tolerance inconsistency ispresent based upon the temperature differentials.

A still further embodiment is a method of creating a compositestructure. The method includes inspecting a surface on which a laminateis to be laid, with IR imaging, reviewing the IR imaging for out oftolerance conditions, and stopping tape layup prior to reaching an outof tolerance condition.

A still further embodiment is a method that includes laying up lanes oftape at a laminate, operating an IR camera to thermally image the lanesof tape, reviewing thermal images to identify ends of the lanes of tape,and determining whether an end of a lane of tape is out of tolerance,and reporting the out of tolerance lane of tape for dispositioning.

Other illustrative embodiments (e.g., methods and computer-readablemedia relating to the foregoing embodiments) may be described below. Thefeatures, functions, and advantages that have been discussed can beachieved independently in various embodiments or may be combined in yetother embodiments further details of which can be seen with reference tothe following description and drawings.

DESCRIPTION OF THE DRAWINGS

Some embodiments of the present disclosure are now described, by way ofexample only, and with reference to the accompanying drawings. The samereference number represents the same element or the same type of elementon all drawings.

FIG. 1 is a block diagram of a tape layup inspection system in anillustrative embodiment.

FIG. 2 is a flowchart illustrating a method for detecting andclassifying features found within a layup for a laminate, based onthermographic images in an illustrative embodiment.

FIG. 3 is a diagram illustrating a tape layup machine in an illustrativeembodiment.

FIG. 4 is a top view of courses laid-up by a tape layup machine in anillustrative embodiment.

FIGS. 5A-5B, 6, and 7 are side views of heads of a tape layup machine inan illustrative embodiment.

FIG. 8 is a flowchart illustrating a method for determining locations ofends of lanes of tape based on a thermographic image in an illustrativeembodiment.

FIG. 9 is a thermographic image of a portion of a course that includesends of lanes of tape in an illustrative embodiment.

FIG. 10 is a flowchart illustrating a method for detecting layupinconsistencies in an illustrative embodiment.

FIG. 11 is a thermographic image of a portion of a course that includesa layup inconsistency in an illustrative embodiment.

FIG. 12 is a flowchart illustrating a method for determining locationsof debris based on a thermographic image in an illustrative embodiment.

FIG. 13 is a thermographic image of a portion of a course that includesdebris in an illustrative embodiment.

FIG. 14 is a flowchart illustrating a method of correlating imagecoordinates with physical locations in an illustrative embodiment.

FIGS. 15-18 illustrate further methods pertaining to thermographicinspection in illustrative embodiments.

FIGS. 19A-19B illustrate further methods pertaining to thermographicinspection in illustrative embodiments.

FIG. 20 is a flow diagram of aircraft production and service methodologyin an illustrative embodiment.

FIG. 21 is a block diagram of an aircraft in an illustrative embodiment.

DESCRIPTION

The figures and the following description provide specific illustrativeembodiments of the disclosure. It will thus be appreciated that thoseskilled in the art will be able to devise various arrangements that,although not explicitly described or shown herein, embody the principlesof the disclosure and are included within the scope of the disclosure.Furthermore, any examples described herein are intended to aid inunderstanding the principles of the disclosure, and are to be construedas being without limitation to such specifically recited examples andconditions. As a result, the disclosure is not limited to the specificembodiments or examples described below, but by the claims and theirequivalents.

As used herein, “tape” may comprise fiber reinforced tapes or slit tapetows. In this disclosure the terms tape and tow are used interchangeablyto indicate strips of material of varying widths. Tapes may be utilizedto fabricate a variety of laminates, including laminates that will becured into composite parts. Composite parts, such as Carbon FiberReinforced Polymer (CFRP) parts, are initially laid-up in a multi-layerlaminate. Individual fibers within each layer of the laminate arealigned parallel with each other within the plane of the laminate, butdifferent layers may exhibit different fiber orientations in order toincrease the strength of the resulting composite along differentdimensions. The laminate may include a viscous resin that solidifies inorder to harden the preform into a composite part (e.g., for use in anaircraft). Carbon fiber that has been impregnated with an uncuredthermoset resin or a thermoplastic resin is referred to as “prepreg.”Other types of carbon fiber include “dry fiber” which has not beenimpregnated with thermoset resin but may include a tackifier or binder.Dry fiber may be infused with resin prior to curing. For thermosetresins, the hardening is a one-way process referred to as curing. Forthermoplastic resins, a hardened (or consolidated) resin may reach aviscous form if it is re-heated.

FIG. 1 is a block diagram of a tape layup inspection system 100 in anillustrative embodiment. Tape layup inspection system 100 comprises anysystem, component, or device operable to lay up tape to form a laminate,and to inspect the laminate for quality control purposes. Tape layupinspection system 100 has been enhanced to utilize thermal imagingdevices mounted to a head of a tape layup machine in order to identifyfeatures that may be pertinent to quality control.

In this embodiment, tape layup inspection system 100 includes inspectionserver 110 and tape layup machine 130. Tape layup machine 130 operateshead 140 in accordance with NC program 135 in order to lay up lanes 160of tape 154 that form one or more layers 152 of laminate 150. Forexample, controller 132 of tape layup machine 130 may direct theoperations of motors 138 based on instructions stored in memory 134, inorder to move head 140 to various locations at laminate 150. Controller132 may further direct tape reserve 136 to provide additional tape totape dispensers 143 of head 140. Controller 132 may be implemented, forexample, as custom circuitry, as a hardware processor executingprogrammed instructions, or some combination thereof.

Head 140 includes tape dispensers 143, which apply lanes 160 of tape 154to surface 156 of laminate 150. Heater 141 and/or heater 144 apply heatthat facilitates tacking of lanes of tape 154 to laminate 150. Forexample, these heaters may heat laminate 150 (or lanes 160 of tape 154)to a temperature at which a thermoplastic or thermoset resin within thelanes of tape 154 either tackifies or becomes molten. Heaters 141 and144 may comprise lasers, infrared heat lamps, etc.

In embodiments where heaters 141 and 144 heat either laminate 150 or thelanes of tape, a substantial temperature difference (e.g., one to fiftydegrees Fahrenheit (F) for thermoset tapes, five hundred to eighthundred degrees Fahrenheit for thermoplastic tapes) exists between thelanes 160 of tape 154 and the laminate 150. This means thatthermographic images (having a sensitivity of, for example, a fifth ofone degree Fahrenheit) will exhibit a high degree of contrast betweenthe lanes 160 of freshly laid tape and the laminate 150.

In embodiments where heaters 141 and 144 are operated to heat the lanes160 of tape 154 and also the laminate 150, foreign objects (which aremade from different types of material) will contrast strongly againstthe underlying laminate material, because they will reach a differenttemperature and have a different thermal emissivity than the laminatematerial in response to being exposed to the same amount of heat.

Head 140 also includes a compaction roller 146, which applies pressureto the lanes 160 of tape 154 (e.g., after the lanes 160 have beentackified), pressing them onto laminate 150 and physically integratingthem into laminate 150. Infrared (IR) cameras 142 and 145 image thelaminate 150 as well as the lanes 160 of tape 154 that are applied tolaminate 150. Position sensors 139 detect the location of head 140 asthermographic images are acquired by IR cameras 142 and 145. Thisenables pixels within the thermographic images to be correlated withreal-world locations at the laminate 150. Position sensors 139 may, forexample, comprise laser or visual tracking systems, rotation and/orextension sensors mounted to actuators within tape layup machine 130,etc.

Thermographic images 118 produced by tape layup machine 130 during layupare processed by inspection server 110. Inspection server 110 includescontroller 112, which analyzes thermographic images 118 stored in memory114, and identifies and classifies features within the thermographicimages 118 based on detection functions 122. Detection functions 122 mayalso include instructions for implementing one or more of the methodsdescribed herein. Controller 112 further determines, based on positiondata 120 acquired from position sensors 139, locations of the featureson the laminate 150. This information may be passed on to a technicianeither as a report or an annotated image of the laminate for review.Controller 112 may be implemented, for example, as custom circuitry, asa hardware processor executing programmed instructions, or somecombination thereof.

Illustrative details of the operation of tape layup inspection system100 will be discussed with regard to FIG. 2. Specifically, FIG. 2illustrates a method for detecting and classifying features found withina layup for a laminate, based on thermographic images. Assume, for thisembodiment, that tape layup machine 130 has been programmed to followinstructions in NC program 135 for laying up a laminate (e.g., alaminate that will be hardened into a composite part). Further, assumethat tape layup machine 130 is loaded with rows of tape (e.g., prepregthermoset or thermoplastic CFRP) and is ready to initiate fabrication ofthe laminate. To this end, the tape layup machine 130 operates head 140to lay up a base layer of the laminate 150 by dispensing one or morecourses comprising lanes of tape.

FIG. 2 is a flowchart illustrating a method for operating a tape layupinspection system in an illustrative embodiment. The steps of method 200are described with reference to tape layup inspection system 100 of FIG.1, but those skilled in the art will appreciate that method 200 may beperformed in other systems. The steps of the flowcharts described hereinare not all inclusive and may include other steps not shown. The stepsdescribed herein may also be performed in an alternative order.

In step 202, head 140 of tape layup machine 130 lays up tape 154 ontosurface 156 of laminate 150. This may comprise following instructions inNC program 135 to cut and/or dispense multiple lanes of tape in acourse. This may further comprise operating compaction roller 146 tophysically integrate the newly dispensed lanes of tape with the laminate150.

In step 204, heater 141 or heater 144 apply heat to tack the lanes oftape to the surface of the laminate 150. Step 204 may occur concurrentlywith, before, or even after step 202. Thus, in many embodiments,laminate 150 or lanes 160 are heated prior to contacting each other. Inembodiments where the tape 154 comprises a prepreg thermoset resin tape,heater 141 may be activated to alter the temperature of the surface oflaminate 150 with respect to ambient temperature before the lanes oftape are applied to the surface. In embodiments where the tape 154comprises prepreg thermoplastic tape, heater 144 may comprise one ormore lasers that heat the tape 154 resulting in a temperaturedifferential from approximately four hundred to eight hundred degreesFahrenheit between the surface of the laminate before the tape 154 isapplied. In either case, the heaters generate a substantial differencein temperature, between the lanes of the tape 154 leaving the tapedispenser 143, and the surface of laminate 150.

In step 206, IR camera 145 generates thermographic images 118 of thelanes 160 of the tape 154 as applied to the laminate 150. Eachthermographic image 118 may depict a portion of all lanes within acourse, and thermographic images 118 may be stitched together to depictthe layup resulting from an entire course. Because lanes may extend fortens of feet, multiple thermographic images 118 may need to be analyzedin order to detect the specific start locations and stop locations ofindividual lanes within a course. Thus, the thermographic images 118 maybe acquired periodically (e.g., once every few seconds, once every tenfeet of movement of head 140, etc.), to ensure that there are no gaps incoverage between images during layup.

In step 208, controller 112 analyzes contrast within the thermographicimages 118 to identify a feature at laminate 150 that is thermallydistinct from its surroundings. Each pixel within a thermographic image118 is assigned a value corresponding with a temperature, and thermallydistinct features may be detected by identifying contiguous sets ofpixels that are within a range of temperatures (e.g., fifty degreesFahrenheit, ten degrees Fahrenheit, etc.) that are surrounded by pixelsoutside of the range (e.g., more than one degree Fahrenheit differentthan the contiguous set of pixels). Each feature may have an associatedtemperature or range of temperatures, a known shape, and a known size interms of width or number of pixels. In further embodiments, athermographic image may be altered by applying an edge detectionalgorithm (such as a Laplacian or other filter) before the image isanalyzed.

In step 210, controller 112 classifies the feature based on at least oneof a size of the feature, a shape of the feature, or a difference intemperature between the feature and its surroundings. For example, lanes160 of tape 154 are expected to exhibit known ranges of temperaturedifferences from an underlying laminate. These ranges are discussedabove. If a region is within the expected range of temperaturedifference with respect to another region, it may be classified based onwhether is hotter or colder than that other region.

In step 212 controller 112 determines features that are out of tolerance(e.g., too large, as identified by a filtering process performed on thefeature's properties). If features are out of tolerance, then controller112 reports the out of tolerance features for review. Thesefeatures/conditions may be reported graphically on a representation oflaminate 150, or in a textual report. During this step, controller 112may further filter the features based on their size and type, in orderto automatically indicate and highlight out of tolerance featureswithout a need for human intervention.

In a further example, a feature that exhibits rounded borders (e.g., apuddle of liquid) may be classified differently than a feature havingsharp, linear edges (e.g., an edge of a lane of tape). Size also plays arole in these determinations, as small features may be indicative ofdebris at the laminate, while large features may be indicative of entirecourses or lanes of tape.

Method 200 provides a substantial advantage over prior inspectiontechniques, because it utilizes differences in temperature, not color,to identify and classify layup features. For example, there is likely tobe a pre-existing temperature difference between layup components (e.g.,because one of them is heated to facilitate tacking), while there islikely to be almost no color difference between the laminate and thelanes of tape in visible light spectra. Therefore, method 200 enablesthe signal to noise ratio of layup inspection techniques to increase byorders of magnitude with respect to prior techniques. Furthermore,because thermal imaging technology is tightly coupled with the head 140of the tape layup machine 130, there is no need for manual imaging ofthe laminate, or other human interactions with the laminate 150. Thisreduces the chance of technicians dropping foreign debris onto thelaminate, stepping on the laminate 150, or otherwise unintentionallyaltering the laminate 150 during human inspection. This also enableslayup inspection to be performed much faster, and to occurcontemporaneously with tape laydown of each course for each layer of thelaminate, especially compared with stopping tape lay down to facilitatehuman access/inspection.

FIG. 3 is a diagram illustrating a tape layup machine 300 that ismounted to a support 370 in an illustrative embodiment. Tape layupmachine 300 comprises any system or device capable of laying up lanes352 of tape that form a laminate 350 (e.g., for curing into a compositepart). Tape layup machine 300 includes head 380, which dispenses lanes352 of tape (e.g., CFRP) during layup. Lanes 352 are laid-up to formlaminate 350, which comprises one or more layers of material that willbe cured into a single monolithic composite part. In this embodiment,laminate 350 comprises a section for an aircraft, and is held in placeby rotational holder 360.

As tape layup machine 300 operates to lay up the lanes 352 of tape ontolaminate 350, tape layup machine 300 may move directly towards/away fromlaminate 350 along axis X 366, vertically upwards/downwards along axis Y364, and/or laterally along axis Z 362. As used herein, when tape layupmachine 300 lays up multiple lanes 352 concurrently during a single“sweep” of head 380, those lanes 352 are collectively referred to as asingle “course.” A set of non-overlapping courses that are appliedconsecutively may be referred to as a layer. As layers are added tolaminate 350, the strength of the resulting composite part is increased.

Laying up material for a laminate 350 that is large (e.g., a section offuselage) is a time-consuming and complex process. In order to ensurethat lanes 352 are laid-up quickly and efficiently, the operations oftape layup machine 300 are controlled by an NC program. In oneembodiment, the NC program provides instructions on a course-by-coursebasis for aligning/repositioning the tape layup machine 300, to controllayup processes all the way down to the application of individualtows/tapes, moving the head 380, and laying up lanes 352 onto laminate350. In this manner, by performing the instructions in the NC program,tape layup machine 300 fabricates a laminate (e.g., a laminate forcuring into a composite part).

FIG. 4 is a top view of courses 420 laid-up by a tape layup machine inan illustrative embodiment, and corresponds with view arrows 4 of FIG.3. FIG. 4 illustrates a laminate 400, which itself comprises lanes oftape that have been tacked together (not shown for clarity). As head 380moves across surface 430 of laminate 400, it deposits a course 420comprising one or more lanes 352 of tape onto the laminate 400. In thisembodiment, each course comprises eight lanes of tows. For fiberreinforced laminates, each lane in a course will exhibit the same fiberdirection, although different courses for different layers of thelaminate may exhibit different fiber directions.

An NC program directing the head 380 may indicate locations at which toplace each lane 352 within a course 420. However, the actual ends of thelanes 352 as placed onto the laminate 400 may vary. Thus, a distance Dmay exist between the actual end location of a lane 353, and theintended end location of the lane 353. Additionally, debris 440 may fallonto the laminate during or after layup, and one or more layupinconsistencies 450 may also occur during the layup process. Debris 440may comprise pills or pulls of fiber at the tape (“fuzz balls”), liquids(e.g., oil or water), particles (e.g., metal shavings, granules ofplastic material, etc.), and a backing for the tape. Layup inconsistency450 may comprise a twisted tape, a folded tape, a bridging of tape, apucker, a wrinkle, an untacked tow or portion thereof, a missing tow, adouble tow, a split or damaged tow, missing material, or otherconditions.

Because thermal imaging may be utilized to quantify aspects of variousfeatures such as the locations of ends of lanes, the locations offoreign debris, and the locations of layup inconsistencies, the time andlabor spent reworking the laminate 400 is reduced. That is, because outof tolerance features of the laminate 400 are immediately detectedduring layup, only a section of a course will need to be dispositioned.Furthermore, because the laminate 400 remains green and uncured duringthe inspection process, the rebuilding process is a simple matter ofdirectly removing and re-applying lanes of tape to the laminate. This isnot possible after the laminate has been cured into a composite part.

FIGS. 5-7 are side views of various configurations of a head 380 of atape layup machine, and corresponds with view arrows 5 of FIG. 4.Specifically, FIGS. 5A-5B illustrate heads configured to inspectthermoset lanes of tape applied to laminates, FIG. 6 illustrates a headconfigured to inspect thermoplastic lanes of tape applied to laminates,and FIG. 7 illustrates a head configured to inspect a laminate fordebris.

FIG. 5A is a side view of a head 380 for inspecting thermoset lanes oftape applied to laminates in an illustrative embodiment. As shown inFIG. 5A, head 380 proceeds in direction 500, and includes a compactionroller 520 for compacting lanes 352 of tape onto surface 430 of laminate400. Heater 530 applies heat (A) to the surface 430, in order toincrease the temperature of surface 430 to a temperature where itsoftens and becomes tacky (i.e., to increase tack for the layer that waspreviously laid-up and is about to be covered up by a new layer).Although heater 530 is shown as being a distance in front of compactionroller 520, in further embodiments the heater 530 is placed immediatelyin front of compaction roller 520. When lanes 352 are applied to surface430, a temperature differential exists between the lanes and theunderlying (e.g., unheated) laminate. This makes the lanes 352distinguishable from the underlying laminate when reviewingthermographic images from IR camera 510, which trails (i.e., is locateddownstream of) compaction roller 520. FIG. 5B illustrates a further viewwherein a heater 532 is disposed upstream of compaction roller 520, andheats tape for one or more lanes 352 prior to the tape reaching thecompaction roller 520.

FIG. 6 is a side view of head 380 for inspecting thermoplastic lanes oftape applied to a laminate in an illustrative embodiment. As shown inFIG. 6, head 380 proceeds in direction 600, and includes a compactionroller 620 for compacting lanes 352 of tape onto surface 430 of laminate400. A heater 632 applies targeted heat (A) to tape within lanes 352 inorder to increase the temperature up to or in excess of thethermoplastic material melt temperature. This heat is applied at or justbefore tape for the lanes 352 is compacted onto laminated 400. Thisenables detection of added or lost lanes of tape, as well as debris.When tape for lanes 352 is applied to surface 430, a temperaturedifferential exists between the lanes and the underlying laminate. Thismakes the lanes distinguishable from the underlying laminate whenreviewing thermographic images from the IR camera 610, which trailscompaction roller 620.

FIG. 7 is a side view of a head 380 for inspecting a laminate in orderto detect debris in an illustrative embodiment. As shown in FIG. 7, head380 proceeds in direction 700, and includes a compaction roller 720 forcompacting lanes 352 of tape onto surface 430 of laminate 400. Head 380also includes heater 730 and IR camera 710, as well as heater 732 and IRcamera 712. Heater 730 applies heat (A) to the surface 430, in order toincrease the temperature of surface 430. Debris 750 (e.g., ForeignObject Debris (FOD), a pill of fiber, etc.) located at surface 430 istherefore heated by heater 730. Because the underlying thermalproperties of the debris are likely to vary from that of surface 430, orbecause the shape of the debris may alter its ability to retain heat ascompared to surface 430 and/or because the shape of the debris may berecognizable via image analysis, the debris 750 may be detected inthermographic images acquired by IR camera 710.

Head 380 additionally includes heater 732 and IR camera 712. Heater 732increases a temperature of lanes 352. This helps IR camera 712 to betterdistinguish between debris 760 (e.g., new debris falling off of head380, such as oil) and the lanes 352. Thus, when debris exists on surface430 before tape for one or more lanes 352 are laid-up, the debris can bedetected by IR camera 710, while debris that lands on lanes 352 afterthe lanes 352 are laid-up can be detected by IR camera 712.

The arrangement depicted in FIG. 7 has an additional advantage in thatthe IR camera 732 may also indirectly detect debris 750. Debris 750often conducts heat differently between lanes 352 and laminate surface430 than does direct contact between lanes 352 and laminate surface 430.If debris 750 is more insulating (i.e., conducts heat worse) than directcontact, or debris 750 induces an air gap (which also insulates) betweenlanes 352 and laminate surface 430, then the area of one or more lanes352 above the debris 750 will appear hotter than surrounding lanes, andthis hot spot may be used as detection of debris 750 buried under lanes352. If debris 750 is more conductive (i.e., conducts heat better) thandirect contact between lanes 352 and laminate surface 430, then the areaof lanes 352 which are above the debris 750 will appear colder than thesurrounding lanes 352, and this cold spot may be used as detection ofdebris 750 buried under lanes 352.

FIGS. 8-13 illustrate various specific techniques for identifying endsof lanes of tape, layup inconsistencies, and debris respectively.Specifically, FIGS. 8-9 describe identifying the ends of lanes of tape,FIGS. 10-11 describe identifying layup inconsistencies, and FIGS. 12-13describe identifying debris.

FIG. 8 is a flowchart illustrating a method 800 for operating a tapelayup inspection system to detect ends of lanes of tape in anillustrative embodiment. The steps of method 800 are described withrespect to tape layup inspection system 100 of FIG. 1, and may beperformed via the head 380 depicted in FIG. 5 or FIG. 6, or even thehead 380 depicted in FIG. 7. Method 800 may initiate with steps 202-206of method 200 described above, to lay up and image lanes of tape at alaminate.

In step 802, controller 112 analyzes contrast within thermographicimages 118 to identify lanes 160 of tape 154. Controller 112 mayidentify values (e.g. intensity levels, or brightness levels) at each ofmultiple pixels within the thermographic images 118. Pixel values withinthe thermographic images correspond with temperatures. Hence, controller112 may identify regions that have different temperatures, based ondifferences between values of neighboring pixels.

This process may include identifying contiguous regions of pixels thathave a temperature differential of more than a predetermined thresholdamount with respect to neighboring contiguous regions of pixels, orgrouping all contiguous pixels that are within a threshold range oftemperatures (e.g., five degrees Fahrenheit, fifty degrees Fahrenheit)together with each other into a region. For example, if the lanes 160 oftape 154 are known to have a temperature differential between one andfifty degrees Fahrenheit with respect to the laminate 150, controller112 may identify contiguous regions of pixels that have a correspondingtemperature differential to surrounding regions as being lanes of tape.

In step 804, controller 112 determines a direction of the lanes 160 oftape 154. The direction of a lane of tape is the direction in which head140 moves while laying up the lane. The direction may be predefinedbased on a known orientation of the camera with respect to the head 140,considered in combination with position data 120 and/or directionsspecified by the NC program 135. Controller 112 may even use positiondata 120 to confirm that the head 140 moves in a direction indicated byNC program 135. Alternatively, the direction or may be dynamicallydetermined based on the longest axis found for lanes depicted within athermographic image.

In step 806, for each lane of tape, controller 112 identifies a boundaryat which temperature changes by more than a threshold amount whenproceeding in the direction determined in step 804. That is, within thebounds of each lane of tape, controller 112 reviews the values ofadjacent/neighboring pixels, while moving pixel-by-pixel in thedirection until a boundary is detected. The threshold amount used forboundary detection may vary between thermoset and thermoplasticmaterials, as discussed above. In some embodiments, step 806 maycomprise running an edge detection algorithm (e.g., applying a Laplacianor other filter) to the thermographic image 118, and identifying regionswhere a sharp transition between temperatures occurs.

In step 808, controller 112 determines a location of a correspondingboundary for each of the lanes 160 of tape 154. This may comprisetransforming coordinates at the thermographic image 118 into locationsat the laminate 150, for example, based upon a known position and/ororientation of an IR camera at the time that the IR camera generated thethermal image, and a known offset between the IR camera and coordinatesof pixels.

In step 810, controller 112 reports locations of the ends of the lanes160 of tape 154, based on the boundaries detected in the thermographicimages. For example, controller 112 may report the locations determinedin step 808, in either a textual report or an overlay provided atop animage of the laminate 150. If the locations of the ends of the lanes 160are more than a threshold amount (e.g., one inch, ten inches, etc.) fromtheir intended start locations and stop locations, controller 112 mayindicate this condition as part of the report. In step 812, controller112 determines whether the ends of the lanes are within tolerance. Ifany of the ends of the lanes are out of tolerance, step 814 comprisesdispositioning these ends. Dispositioning may include any type ofdetermination of the course of action to deal with a discovered out oftolerance condition for an end.

FIG. 9 is a thermographic image 900 of a portion of a course in anillustrative embodiment. Within the thermographic image, pixels thatrepresent objects having different temperatures will have differentvalues (e.g., levels of brightness). Thus, a pixel for a cool object mayappear darker than a pixel for a warm object. Controller 112 may analyzethermographic image 900 by applying an edge-detection algorithm, orotherwise searching for transitions in temperature along the Y direction930 that are greater than a threshold amount (e.g., greater than onedegree Fahrenheit). Controller 112 may then determine a location andthickness of each lane depicted within the thermographic image 900.Fibers may be oriented in any suitable direction within each of thelanes of tape. For example, a region 922 depicting a top lane has awidth W1, a region 924 depicting a middle lane has a width W2, and aregion 926 depicting bottom lane has a width W3. These regions aresurrounded by region 920, which represents the underlying laminate (asdetermined by differences in temperature). Within the Y coordinatesoccupied by each lane, controller 112 may traverse pixels in the Xdirection 940 to identify boundaries 910 between pixels that are greaterthan the threshold. For each boundary 910 identified in this manner,controller 112 may identify the X and Y coordinate of the boundary 910within the image as the end of a lane. For example, the top lane ends atX1, the middle lane ends at X2, and the bottom lane ends at X3. Inembodiments where the boundaries comprise regions of pixels, controller112 may calculate a centroid of the region, and use the coordinate ofthe centroid. The coordinates may be transformed into locations at thelaminate 150 based on position data 120, and the locations may becompared against desired locations indicated in an NC program. If thelocations are more than a threshold distance (e.g., one foot, one inch,etc.) from the desired locations, then a technician may elect to pauselayup processes for the laminate, in order to disposition (e.g., rework)any out-of-tolerance conditions. In addition, a statistical report maybe provided to the technician that compares desired lane locations tothe identified lane locations for each layer.

FIG. 10 is a flowchart illustrating a method 1000 for detecting layupinconsistencies in an illustrative embodiment. The steps of method 1000are described with respect to tape layup inspection system 100 of FIG.1, and may be performed via the head 380 depicted in FIG. 5 or FIG. 6,or even the head 380 depicted in FIG. 7. Method 1000 may initiate withsteps 202-206 of method 200 described above, to lay up and image lanesof tape at a laminate.

Step 1002 includes analyzing contrast within thermographic images 118 toidentify lanes 160 of tape 154. This may be performed based on anexpected amount of temperature difference between the laminate 150 andthe lanes 160, and may be performed in a similar manner to the steps ofmethod 800 provided above.

In step 1004, for each lane of tape, controller 112 reviews an interiorof the lane for differences in temperature. These differences intemperature may be low enough that the interior of the lane is notconsidered a different region, but may be high enough (to indicate thata inconsistency may exist. Step 1004 therefore facilitates detection oflayup inconsistencies found within a lane of tape.

In step 1006, for each lane of tape, controller 112 reviews a boundaryof the lane for inconsistencies in shape. For example, lanes may beexpected to have boundaries that are roughly rectangular in shape, andare composed of long straight lines. If a boundary exhibits a highcurvature or irregularity, this may indicate the presence of a layupinconsistency. Step 1006 therefore facilitates detection of layupinconsistencies found at the edge of one or more lanes of tape.

In step 1008, controller 112 determines the existence of a layupinconsistency, for example based upon the reviews of step 1004 and step1006. In step 1010, controller 112 categorizes the layup inconsistencybased on at least one of a size of the layup inconsistency, a shape ofthe layup inconsistency, or a difference in temperature at the layupinconsistency. For example, detection functions 122 may indicate that ainconsistency exists if the width of a tow changes to less than apredetermined amount, if a gap between tows increases beyond ordecreases below a threshold value, if a boundary of a tow is jagged,etc. Different ones of detection functions 122 may be triggered (andhence different categories of inconsistency may be assigned bycontroller 112) based on various combinations of shape, size, andtemperature. In step 1012, controller 112 identifies out-of-tolerancelayup inconsistencies, and in step 1014, controller 112 reports out oftolerance layup inconsistencies for review (e.g., in order to enable atechnician to engage in dispositioning of the out of toleranceconditions.

FIG. 11 is a thermographic image 1100 of a portion of a course thatincludes layup inconsistencies in an illustrative embodiment. Within thethermographic image, pixels that represent objects having differenttemperatures will have different values (e.g., levels of brightness).Thus, a pixel for a cool object may appear darker than a pixel for awarm object. The lanes have a length along the X direction 1160, andwidth along the Y direction 1150. In this embodiment, lanes 1122 and1124 do not include inconsistencies, while lane 1126 includes layupinconsistencies 1130 in the form of a pucker, and layup inconsistency1140 in the form of a wrinkle. Layup inconsistencies 1130 may bedetermined based on lane 1126 dropping below an expected width or havinga varying width, or may be detected by determining that a curvature ofthe edge of lane 1126 changes or is within a predefined range. Layupinconsistencies may also be detected by temperature differences (beyonda threshold) between lane 1126 and an underlying layer 1120 of thelaminate. Meanwhile, layup inconsistency 1140 may be detected based onits long, narrow shape, and having a known temperature difference withrespect to the rest of the lane 1126.

FIG. 12 is a flowchart illustrating a method 1200 for determininglocations of debris based on a thermographic image in an illustrativeembodiment, and may be performed via the head 380 depicted in FIG. 7.The steps of method 1200 are described with respect to tape layupinspection system 100 of FIG. 1, but may be performed in other systemsas desired. Method 1200 includes heating a surface 156 of laminate 150via heater 141 in step 1202, and generating thermographic images 118 ofthe surface 156 via IR camera 142 in step 1204. Method 1200 alsoincludes laying up lanes 160 of tape 154 onto the surface 156 oflaminate 150 via tape dispensers 143 in step 1206. In step 1208, method1200 includes heating the lanes 160 of tape 154 via heater 144, and step1210 includes generating thermographic images of the lanes 160 of tape154 as applied to the laminate 150. Ideally, the lanes 160 are heated tothe same temperature as the laminate 150. This enables debris (e.g.,FOD) to be more easily distinguished from the tape 154 that lanes 160and laminate 150 are made from.

Having acquired the thermographic images 118 depicting both the laminate150 and the lanes 160 applied to the laminate 150, foreign object debriscan be spotted accurately and efficiently by identifying differences intemperature. In step 1212, controller 112 analyzes contrast within thethermographic images to identify different regions having differenttemperatures, which may be performed in a similar manner to thetechniques described above. However, because different categories ofdebris may be associated with substantially different thermalproperties, regions may be distinguished based on a variety of differenttemperature thresholds, each corresponding to a different type ofdebris. For example, pills of fiber at the tape may be expected to be afirst range of temperatures higher than the underlying laminate, to besmall in size and to have irregular borders, while liquids may beexpected to be a second range of temperatures cooler than the underlyinglaminate, have a wide range of sizes, and have smooth borders. Thus, theamount of temperature difference used as criteria to define separateregions in method 1200 (e.g., less than five degrees, less than twodegrees, etc.) may be much smaller than the amount of temperaturedifference described with respect to other methods.

Because thermographic images are acquired both before and after layingup lanes of tape, analyzing contrast within the thermographic images maycomprise reviewing the thermographic images of the surface of thelaminate to identify debris covered by at least one layer of tape, andalso reviewing the thermographic images of the lanes of tape as appliedto the laminate to identify debris at a surface of the lanes of tape.The process may even be stopped prior to laying up a course over an outof tolerance piece of debris detected by IR camera 710. This allowsdisposition (e.g. removal of the piece of debris) prior to applying thecourse over the debris. If the debris is not out of tolerance, applyinga course over it might be a desired action. To facilitate detection ofdebris at boundaries between lanes or courses, images may have a wideenough field of view to capture likely locations at which the debriswill be located.

In step 1214, controller 112 categorizes a type of debris within aregion based upon at least one of a size of the region, a shape of theregion, or a difference in temperature between the region and otherregions. For example, pills of fiber may be expected to have irregularshapes, to have a specific amount of temperature differential from theunderlying laminate, and to be small (e.g., having a maximum number ofpixels corresponding with an area of less than a centimeter across).Particles such as metal shavings may be expected to be particularlysmall or a different temperature than their surroundings, and liquidsmay be expected to be have a different range of temperaturedifferentials with their surroundings, and also to have rounded borders.Furthermore, in some embodiments metal shavings of any size areconsidered out of tolerance, while pills below a certain size might beconsidered within tolerance. Detection functions 122 may indicateconditions for categorizing each of a variety of regions at a laminateinto categories of debris. After debris has been categorized andidentified by controller 112, controller 112 may generate a reportindicating the nature, location, and/or severity of the debris that wasdetected. In step 1216, debris that is out of tolerance is identified(e.g., based on its size and classification) by controller 112, and instep 1218, out of tolerance debris is reported to a technician fordispositioning (e.g., removal).

FIG. 13 is a thermographic image 1300 of a portion of a course thatincludes debris in an illustrative embodiment. Within the thermographicimage, pixels that represent objects having different temperatures willhave different values (e.g., levels of brightness). Thus, a pixel for acool object may appear darker than a pixel for a warm object. In thisembodiment, the course includes lane 1322, lane 1324, and lane 1326.Lane 1322 includes debris in the form of a metal pellet 1330 thathappens to be hotter than its surroundings, and lane 1326 includesdebris in the form of a liquid puddle 1340 that happens to be coolerthan its surroundings. In this case, the metal pellet 1330 straddles aboundary of lane 1322 and an underlying laminate 1320. The coursesproceed In the X direction 1360, and have a width along the Y direction1350.

FIG. 14 is a flowchart illustrating a method 1400 of correlating imagecoordinates with physical locations in an illustrative embodiment. Instep 1402 of method 1400, controller 1412 determines a position and/ororientation of an IR camera 145 at the time when a thermographic imagewas generated by the IR camera 145. This may come in the form ofposition data 120 reported by position sensors 139 of FIG. 1. In step1404, controller 112 determines a coordinate (e.g., an X and Y position)of a feature depicted within the thermographic image. This may compriseidentifying a region having a different temperature than neighboringregions, and calculating a centroid of the region.

Step 1406 includes determining a location at the laminate based on theposition of the IR camera 145 and the coordinate of the feature. Forexample, position data may indicate a position and orientation of the IRcamera 145 when the thermographic image was taken. Because the camera isfixed with respect to a head of a tape layup machine, each coordinatewithin all images may correspond with a known physical offset from theIR camera 145. Hence, by applying the offset, the actual location of afeature at the laminate can be reliably determined.

FIG. 15 illustrates a method 1500 of controlling a tape laying processin an illustrative embodiment. The method includes laying up tape onsurface (step 1502), and while laying up the tape, inspecting thesurface on which it is laid up as well as the laid up tape using IRimaging (step 1504). The method further comprises reviewing the IRimaging for out of tolerance conditions, and stopping the tape laying ifan out of tolerance condition is detected (step 1508).

FIG. 16 illustrates a method 1600 of detecting out of toleranceinconsistencies during a tape laying process in an illustrativeembodiment. The method includes heating a surface on which a tape willbe applied (step 1602), acquiring an IR image of the surface (step1604), and determining that an out of tolerance inconsistency isdepicted in the IR image (step 1606).

FIG. 17 illustrates a method 1700 of inspecting a composite surface inan illustrative embodiment. Method 1700 includes creating temperaturedifferentials on a surface that has been heated (step 1702), detectingthe temperature differentials on the surface (step 1704), anddetermining that an out of tolerance inconsistency is present based uponthe temperature differentials (step 1706).

FIG. 18 illustrates a method 1800 of creating a composite structure inan illustrative embodiment. The method includes inspecting a surface onwhich a laminate is to be laid (step 1802), with IR imaging. The methodalso includes reviewing the IR imaging for out of tolerance conditions(step 1804) and stopping tape layup prior to reaching an out oftolerance condition (step 1806).

FIGS. 19A-19B illustrate methods 1900 and 1950 of inspecting tape endlayup in an illustrative embodiment. Method 1900 includes laying uplanes of tape at a laminate (step 1902), operating an IR camera tothermally image the lanes of tape (step 1904), reviewing thermal imagesto identify ends of the lanes of tape (step 1906), determining whetheran end of a lane of tape is out of tolerance (step 1908), and reportingthe out of tolerance lane of tape for dispositioning (step 1910).

FIG. 19B illustrates method 1950 for inspecting tape end layup. Method1950 if focused upon heating the tape prior to placing the tape, inorder to improve tack. Method 1950 may be used to detect out oftolerance inconsistencies during a tape laying process in anillustrative embodiment. The method includes heating tape prior toapplication of the tape onto a surface (step 1952), acquiring an IRimage of the surface (step 1954), and determining that an out oftolerance inconsistency is depicted in the IR image (step 1956).

EXAMPLES

Referring more particularly to the drawings, embodiments of thedisclosure may be described in the context of aircraft manufacturing andservice in method 2000 as shown in FIG. 20 and an aircraft 2002 as shownin FIG. 21. During pre-production, method 2000 may include specificationand design 2004 of the aircraft 2002 and material procurement 2006.During production, component and subassembly manufacturing 2008 andsystem integration 2010 of the aircraft 2002 takes place. Thereafter,the aircraft 2002 may go through certification and delivery 2012 inorder to be placed in service 2014. While in service by a customer, theaircraft 2002 is scheduled for routine work in maintenance and service2016 (which may also include modification, reconfiguration,refurbishment, and so on). Apparatus and methods embodied herein may beemployed during any one or more suitable stages of the production andservice described in method 2000 (e.g., specification and design 2004,material procurement 2006, component and subassembly manufacturing 2008,system integration 2010, certification and delivery 2012, service 2014,maintenance and service 2016) and/or any suitable component of aircraft2002 (e.g., airframe 2018, systems 2020, interior 2022, propulsionsystem 2024, electrical system 2026, hydraulic system 2028,environmental 2030).

Each of the processes of method 2000 may be performed or carried out bya system integrator, a third party, and/or an operator (e.g., acustomer). For the purposes of this description, a system integrator mayinclude without limitation any number of aircraft manufacturers andmajor-system subcontractors; a third party may include withoutlimitation any number of vendors, subcontractors, and suppliers; and anoperator may be an airline, leasing company, military entity, serviceorganization, and so on.

As shown in FIG. 21, the aircraft 2002 produced by method 2000 mayinclude an airframe 2018 with a plurality of systems 2020 and aninterior 2022. Examples of systems 2020 include one or more of apropulsion system 2024, an electrical system 2026, a hydraulic system2028, and an environmental system 2030. Any number of other systems maybe included. Although an aerospace example is shown, the principles ofthe invention may be applied to other industries, such as the automotiveindustry.

As already mentioned above, apparatus and methods embodied herein may beemployed during any one or more of the stages of the production andservice described in method 2000. For example, components orsubassemblies corresponding to component and subassembly manufacturing2008 may be fabricated or manufactured in a manner similar to componentsor subassemblies produced while the aircraft 2002 is in service. Also,one or more apparatus embodiments, method embodiments, or a combinationthereof may be utilized during the subassembly manufacturing 2008 andsystem integration 2010, for example, by substantially expeditingassembly of or reducing the cost of an aircraft 2002. Similarly, one ormore of apparatus embodiments, method embodiments, or a combinationthereof may be utilized while the aircraft 2002 is in service, forexample and without limitation during the maintenance and service 2016.For example, the techniques and systems described herein may be used formaterial procurement 2006, component and subassembly manufacturing 2008,system integration 2010, service 2014, and/or maintenance and service2016, and/or may be used for airframe 2018 and/or interior 2022. Thesetechniques and systems may even be utilized for systems 2020, including,for example, propulsion system 2024, electrical system 2026, hydraulic2028, and/or environmental system 2030.

In one embodiment, a part comprises a portion of airframe 2018, and ismanufactured during component and subassembly manufacturing 2008. Thepart may then be assembled into an aircraft in system integration 2010,and then be utilized in service 2014 until wear renders the partunusable. Then, in maintenance and service 2016, the part may bediscarded and replaced with a newly manufactured part. Inventivecomponents and methods may be utilized throughout component andsubassembly manufacturing 2008 in order to fabricate laminates that arehardened into new parts.

Any of the various control elements (e.g., electrical or electroniccomponents) shown in the figures or described herein may be implementedas hardware, a processor implementing software, a processor implementingfirmware, or some combination of these. For example, an element may beimplemented as dedicated hardware. Dedicated hardware elements may bereferred to as “processors”, “controllers”, or some similar terminology.When provided by a processor, the functions may be provided by a singlededicated processor, by a single shared processor, or by a plurality ofindividual processors, some of which may be shared. Moreover, explicituse of the term “processor” or “controller” should not be construed torefer exclusively to hardware capable of executing software, and mayimplicitly include, without limitation, digital signal processor (DSP)hardware, a network processor, application specific integrated circuit(ASIC) or other circuitry, field programmable gate array (FPGA), readonly memory (ROM) for storing software, random access memory (RAM),non-volatile storage, logic, or some other physical hardware componentor module.

Also, a control element may be implemented as instructions executable bya processor or a computer to perform the functions of the element. Someexamples of instructions are software, program code, and firmware. Theinstructions are operational when executed by the processor to directthe processor to perform the functions of the element. The instructionsmay be stored on storage devices that are readable by the processor.Some examples of the storage devices are digital or solid-statememories, magnetic storage media such as a magnetic disks and magnetictapes, hard drives, or optically readable digital data storage media.

Although specific embodiments are described herein, the scope of thedisclosure is not limited to those specific embodiments. The scope ofthe disclosure is defined by the following claims and any equivalentsthereof

What is claimed is:
 1. A method for performing tape layup inspection,the method comprising: heating a surface of a laminate; generatingthermographic images of the surface; laying up lanes of tape onto thesurface of the laminate; heating the lanes of tape; generatingthermographic images of the lanes of tape as applied to the laminate;analyzing, via a controller, contrast within thermographic images toidentify regions having different temperatures; and categorizing, viathe controller, a type of debris within a region based upon at least oneof a size of the region, a shape of the region, or a difference intemperature between the region and other regions.
 2. The method of claim1 wherein: pixel values within the thermographic images correspond withtemperatures, and the method further comprises: identifying regions thathave different temperatures, based on differences between values ofneighboring pixels; and assigning neighboring pixels that havedifferences in temperature of more than one degree Fahrenheit todifferent regions.
 3. The method of claim 1 wherein: categories ofdebris are selected from the group consisting of: pills of fiber at thetape, liquids, particles, and a backing for the tape.
 4. The method ofclaim 1 further comprising: determining a location of the debris by:determining a position of an infrared camera at a time when thethermographic image was generated; determining a coordinate of a regionas depicted within the thermographic image; and determining a locationat the laminate corresponding with the region based on the position ofthe infrared camera and the coordinate of the region.
 5. The method ofclaim 1 wherein: analyzing contrast within thermographic imagescomprises: reviewing the thermographic images of the surface of thelaminate to identify debris covered by at least one layer of the tape,and reviewing the thermographic images of the lanes of tape as appliedto the laminate to identify debris at a surface of the lanes of tape. 6.The method of claim 1 wherein: the tape comprises a fiber reinforcedmaterial.
 7. The method of claim 1 wherein: the tape layup machine isselected from the group consisting of: Automated Fiber Placement (AFP)machines and Automated Tape Layup (ATL) machines.
 8. A portion of anaircraft assembled according to the method of claim
 1. 9. A method forperforming tape layup inspection, the method comprising: laying up lanesof tape onto a surface of a laminate; heating the lanes of tape;generating thermographic images of the lanes of tape as applied to thelaminate; analyzing, via a controller, contrast within thermographicimages to identify regions having different temperatures; andcategorizing, via the controller, a type of debris within a region basedupon at least one of a size of the region, a shape of the region, or adifference in temperature between the region and other regions.
 10. Themethod of claim 9 wherein: pixel values within the thermographic imagescorrespond with temperatures, and the method further comprises:identifying regions that have different temperatures, based ondifferences between values of neighboring pixels; and assigningneighboring pixels that have differences in temperature of more than onedegree Fahrenheit to different regions.
 11. The method of claim 9wherein: categories of debris are selected from the group consisting of:pills of fiber at the tape, liquids, particles, and a backing for thetape.
 12. The method of claim 9 further comprising: determining alocation of the debris by: determining a position of an infrared cameraat a time when the thermographic image was generated; determining acoordinate of a region as depicted within the thermographic image; anddetermining a location at the laminate corresponding with the regionbased on the position of the infrared camera and the coordinate of theregion.
 13. The method of claim 9 wherein: analyzing contrast withinthermographic images comprises: reviewing the thermographic images ofthe surface of the laminate to identify debris covered by at least onelayer of the tape, and reviewing the thermographic images of the lanesof tape as applied to the laminate to identify debris at a surface ofthe lanes of tape.
 14. The method of claim 9 wherein: the tape comprisesa fiber reinforced material.
 15. The method of claim 9 wherein: the tapelayup machine is selected from the group consisting of: Automated FiberPlacement (AFP) machines and Automated Tape Layup (ATL) machines.
 16. Aportion of an aircraft assembled according to the method of claim
 9. 17.A tape layup inspection system comprising: a head of a tape layupmachine, comprising: tape dispensers that lay up lanes of tape onto asurface of a laminate; a heating element disposed upstream of the tapedispensers that applies heat to the surface prior to laying up thelanes; an infrared camera disposed upstream of the tape dispensers thatgenerates thermographic images of the surface of the laminate; a heatingelement disposed downstream of the tape dispensers that applies heat tothe lanes after laying up the lanes; an infrared camera disposeddownstream of the tape dispensers that generates thermographic images ofthe lanes of tape as applied to the laminate; and a controller that isconfigured to acquire thermographic images from the infrared cameras,analyze contrast within thermographic images to identify regions havingdifferent temperatures, and categorize a type of debris within a regionbased upon at least one of a size of the region, a shape of the region,or a difference in temperature between the region and other regions. 18.The system of claim 17 wherein: pixel values within the thermographicimages correspond with temperatures, and the controller furtheridentifies regions that have different temperatures, based ondifferences between values of neighboring pixels, and assignsneighboring pixels that have differences in temperature of more than onedegree Fahrenheit to different regions.
 19. The system of claim 17wherein: categories of debris are selected from the group consisting of:pills of fiber at the tape, liquids, particles, and a backing for thetape.
 20. The system of claim 17 wherein: the controller determines alocation of the debris by: determining a position of the infrared cameraat a time when the thermographic image was generated; determining acoordinate of a region as depicted within the thermographic image; anddetermining a location at the laminate corresponding with the regionbased on the position of the infrared camera and the coordinate of theregion.
 21. The system of claim 17 wherein: the controller analyzescontrast within thermographic images by: reviewing the thermographicimages of the surface of the laminate to identify debris covered by atleast one layer of the tape, and reviewing the thermographic images ofthe lanes of tape as applied to the laminate to identify debris at asurface of the lanes of tape.
 22. The system of claim 17 wherein: thetape comprises a fiber reinforced material.
 23. The system of claim 17wherein: the tape layup machine is selected from the group consistingof: Automated Fiber Placement (AFP) machines and Automated Tape Layup(ATL) machines.
 24. The system of claim 17 wherein: the laminatecomprises a portion of an aircraft.
 25. The method of claim 9 furthercomprising: heating the surface of the laminate; and generatingthermographic images of the surface of the laminate.